The primary purpose of this project is to elucidate the relationships between use of primary care services and use of mental health services by children in a cohort of children continuously enrolled in an organized health setting for at least six years. Major aspects of the project involve the degree to which there is constancy of utilization patterns over time (high users remaining high users and low users remaining low users,) the degree to which patterns of use can be explained by morbidity (both psychosocial and biological), the association of patterns of use and type of use and demographic characteristics of the child and family, and the extent to which patterns of use (both psychiatric and non-psychiatric) cluster in families. Although the major focus of the research is on high utilizers because of their impact on costs of care, possible consequences of consistently low use on receipt of necessary preventive services will be examined in order to assure that the quality of health care does not suffer when use is low. The study will involve the use of data from a computerized encounter-based information system and review of medical records in a prepaid group practice.